The overall goal of this project is to identify the structure-function relationship of type II collagen as it relates to the pathogenesis of collagen-induced arthritis. It has previously been shown that immunization of susceptible mice with native type II collagen results in the development of polyarthritis which sufficiently resembles human rheumatoid arthritis to be used as a model. There is considerable evidence that the experimental arthritis is dependent upon the presence of specific anticollagen antibody but there is no correlation between antibody level and arthritis. The objective of this project is to identify the structural basis of epitopes on native types II collagen recognized by antibodies which induce or suppress arthritis. Type II collagen will be cleaved with cyanogen bromide and the resulting fragments isolated. Since the topograhic location of these fragments in native type II collagen is precisely known, they will be used as highly-specific probes to identify antibodies critical either to the induction of arthritis or to its prevention. Induction of arthritis and antibody specificity are both highly-dependent on the conformational integrity of the type II collagen molecule. Therefore, it will be necessary to renature each of the fragments before using it as a probe. Once all of the fragments are renatured, they will be used to study cross-reactivity of antisera from both arthritis-susceptible and non-susceptible mouse strains. They will also be used to absorb arthritogenic activity from concentrated polyclonal antibody preparations known to be capable of transferring arthritis. Finally, they will be used to identify and characterize monoclonal antibodies capable of inducing or preventing arthritis. Characterization of arthritogenic epitopes on type II collagen will facilitate further studies of the pathogenesis of collagen-induced arthritis and will permit better focused studies of patients with anticollagen reactivity.